There is a continuous stride to improve the ways to calibrate color images generated by electronic systems, such as scanners, displays, printers, etc. With the increasing use of light emitting diodes (LEDs) in a variety of applications, many manufacturers of devices that employ LEDs need efficient and reliable schemes to ensure quality and consistency in their products.
However, it is well known that due to various reasons, LEDs do not exhibit consistent characteristics. For example, various batches of LEDs manufactured under similar factory conditions generate light that falls within a range of physical properties. Furthermore, those LEDs that have exact same characteristics at the outset, may perform differently over time due to dissimilar use and aging process.
An exemplary use of LEDs is in the process of generating a white light by employing primary colors of Red, Green and Blue (RGB) LEDs. For example, many LCD monitors use an array of red, green and blue LEDs to generate a white backlight. In order to ensure that the white light has a consistent color temperature and intensity, many manufacturers employ complex calibration schemes which lead to higher manufacturing costs.
The reason that it is difficult to ensure that a device such as a monitor generates a consistent white backlight is that the color coordinates for each of the red, green and blue light sources are hard to measure. In accordance with one prior art scheme, it is possible to measure the color coordinates for each primary red, green and blue light sources by performing a sequential measurement procedure as explained below.
During the first step of this sequential procedure, the red and green light sources are turned off, and only the blue primary color point is measured. Then, the red and blue light sources are turned off, and the green primary color point is measured. Finally, the green and blue light sources are turned off, and the red primary color point is measured. However, this scheme does not have a high numerical accuracy, as will be explained in more detail in reference with FIGS. 4 and 5.
Thus, there is a need for a system that can accurately and economically measure the color coordinates for each of the primary red, green and blue light sources, such as LEDs, so as to generate a consistent and desired white light, or for that matter, any light that employs these three primary light sources.